Narrowband internet-of-things (nbiot) physical downlink control channel (pdcch) monitoring optimization in non-terrestrial networks (ntn)

ABSTRACT

Methods and apparatuses for monitoring NPDCCH in NBIoT are disclosed. A method comprises receiving a first control signal scheduling a data transmission; and monitoring a second control signal from a start time slot to an end time slot, wherein the start time slot is a gap period behind the last time slot for receiving the first control signal, and the end time slot is a time period ahead of the first time slot for the data transmission.

FIELD

The subject matter disclosed herein generally relates to wirelesscommunications, and more particularly relates to methods and apparatusesfor NBIoT NPDCCH monitoring optimization in non-terrestrial network(NTN).

BACKGROUND

The following abbreviations are herewith defined, at least some of whichare referred to within the following description: Third GenerationPartnership Project (3GPP), New Radio (NR), European TelecommunicationsStandards Institute (ETSI), Frequency Division Duplex (FDD), FrequencyDivision Multiple Access (FDMA), Long Term Evolution (LTE), New Radio(NR), Very Large Scale Integration (VLSI), Random Access Memory (RAM),Read-Only Memory (ROM), Erasable Programmable Read-Only Memory (EPROM orFlash Memory), Compact Disc Read-Only Memory (CD-ROM), Local AreaNetwork (LAN), Wide Area Network (WAN), Personal Digital Assistant(PDA), User Equipment (UE), Uplink (UL), Evolved Node B (eNB), NextGeneration Node B (gNB), Downlink (DL), Central Processing Unit (CPU),Graphics Processing Unit (GPU), Field Programmable Gate Array (FPGA),Dynamic RAM (DRAM), Synchronous Dynamic RAM (SDRAM), Static RAM (SRAM),Liquid Crystal Display (LCD), Light Emitting Diode (LED), Organic LED(OLED), Orthogonal Frequency Division Multiplexing (OFDM), RadioResource Control (RRC), Time-Division Duplex (TDD), Time DivisionMultiplex (TDM), User Entity/Equipment (Mobile Terminal) (UE), Uplink(UL), Universal Mobile Telecommunications System (UMTS), PhysicalDownlink Shared Channel (PDSCH), Physical Uplink Shared Channel (PUSCH),Physical Uplink Control Channel (PUCCH), Physical Downlink ControlChannel (PDCCH), Downlink control information (DCI), single DCI (S-DCI),transmission reception point (TRP), multiple TRP (multi-TRP or M-TRP),frequency range 2 (FR2), Quasi Co-Location (QCL), channel stateinformation reference signal (CSI-RS), CSI-RS Resource Indicator (CRI),Code Division Multiplexing (CDM), Transmission Configuration Indication(TCI), Sounding Reference Signal (SRS), Control Resource Set (CORESET),Synchronization Signal (SS), reference signal (RS), non-terrestrialnetworks (NTN), terrestrial network (TN), Transport Block (TB),Internet-of-Things (IoT), Narrowband Internet-of-Things (NB-IoT orNBIoT), NBIoT PUSCH (NPUSCH), NBIoT PDCSH (NPDSCH), NBIoT PDCCH(NPDCCH), Machine-Type Communication (MTC), MTC PDCCH (MPDCCH), receiverand transmitter distance (RTD), Hybrid Automatic Repeat reQuest (HARQ),Geostationary Earth Orbit (GEO), Low Earth orbit (LEO).

For NBIoT, DCI Format N0 (referred to as DCI N0 hereinafter) is used totrigger a NPUSCH format 1 uplink transmission. When an NBIoT UE receivesa DCI N0 on NPDCCH at time slot n (hereinafter, time slot is referred toas subframe), it schedules the NPUSCH format 1 uplink transmission atsubframe n+k. When the maximum HARQ process number is equal to 2, theNBIoT UE has to monitor a second DCI N0 after receiving a first DCI N0.

As shown in FIG. 1 , if the NBIoT UE detects NPDCCH with DCI N0 (e.g. afirst DCI N0) ending in subframe n, and if the corresponding NPUSCHformat 1 transmission starts from n+k, the UE is required to monitor anNPDCCH candidate (for a second DCI N0) in subframes starting fromsubframe n+1 to subframe n+k−3 for a second DCI N0, and is not requiredto monitor an NPDCCH candidate in subframes starting from subframe n+k−2to subframe n+k−1.

As the maximal HARQ process number is 2, UE continues to monitor theNPDCCH from subframe n+1 to subframe n+k−3 for a next DCI N0 (i.e. asecond DCI N0). However, as there should be 2 subframes (subframe n+k−2and subframe n+k−1) used for switching before the NPUSCH transmission,UE will not monitor NPDCCH at these 2 subframes (subframe n+k−2 andsubframe n+k−1).

The long receiver and transmitter distance (RTD) in NTN has an impact ontiming relationship of NR (New Radio). An offset K_(offset) can beintroduced to modify relevant timing relationships. For example, for thetransmission timing of DCI scheduled PUSCH (including CSI on PUSCH), theslot allocated for the PUSCH can be modified to be

$\left\lfloor {n \cdot \frac{2^{\mu_{PUSCH}}}{2^{\mu_{PDCCH}}}} \right\rfloor + K_{2} + {K_{offset}.}$

For the transmission timing of RAR grant scheduled PUSCH, the UEtransmits the PUSCH in slot n+K₂+ΔαK_(offset) for the corresponding DCIin slot n. K₂ is the scheduling delay indicated in DCI and μ_(PUSCH) andμ_(PDCCH) are the parameters corresponding to the subcarrier spacerelated to the PUSCH and PDCCH. For example, for subcarrier space ofPUSCH is 15 KHz, μ_(PUSCH) is equal to 1, while for subcarrier space ofPDCCH is 30 KHz, μ_(PDCCH) is equal to 2.

For NBIoT in NTN, it is straightforward to introduce the timing offsetK_(offset) and apply it to modify the timing relationships (similar toNR NTN).

For example, as shown in FIG. 2 , for the transmission timing of DCIscheduled NPUSCH in NBIoT legacy, the UE transmits the NPUSCH fromsubframe n+k₀ (i.e. k=k₀).

As shown in FIG. 2 , the scheduling delay (k₀) between the DCI (i.e. DCIN0) and the corresponding NPUSCH (i.e. NPUSCH format 1) is indicated byDCI N0. In particular, the scheduling delay (k₀) depends on thescheduling delay index (I_(Delay)) and the preconfigured maximaltransmission repetitions of control signal (R_(max)), i.e. maximumnumber of repetitions of NPDCCH carrying the DCI N0, as shown in belowTable 1. The scheduling delay index (I_(Delay)) is contained in the DCIN0. The maximal transmission repetitions of control signal (R_(max)) ispreconfigured by higher layer.

TABLE 1 k₀ I_(Delay) R_(max) < 128 R_(max) ≥ 128 0 0 0 1 4 16 2 8 32 312 64 4 16 128 5 32 256 6 64 512 7 128 1024

On the other hand, as shown in FIG. 3 , for the transmission timing ofDCI scheduled NPUSCH in NBIoT in NTN, the UE may transmit the NPUSCHfrom subframe n+k₀+K_(offset) (i.e. k=k₀+K_(offset)). k₀ is determined(or indicated) by DCI N0. K_(offset) is related to the round tripdistance from the UE and eNB. K_(offset) can be configured in SIB or RRCsignaling. If the UE has its location information and the earth orbitand ephemeris information, the UE can calculate the round trip delayfrom the eNB and UE by itself. The earth orbit and ephemeris informationindicates the position where the satellite is. In other words, theK_(offset) can be alternatively determined by the UE itself. The valueof the K_(offset) may be determined by types of satellites. For example,if the eNB is on LEO, K_(offset) can be tens of milliseconds, while ifthe eNB is on GEO, K_(offset) can be hundreds of milliseconds.

In the condition that the maximal HARQ process number for uplinktransmission (NPUSCH format 1 transmission) is configured to 2 in NBIoT,when the scheduling delay between the DCI and the corresponding NPUSCHis extended to k₀+K_(offset), the UE would continue to monitor theNPDCCH for a next DCI in the following UE specific search space, i.e.the delay period except for the last two subframes before the NPUSCHtransmission that are used for switching. However, due to long RTD inNTN, the delay k₀+K_(offset) would be quite long. Therefore, unnecessarypower consumption may be present in monitoring the next DCI in the UEspecific search space.

This disclosure targets for saving power for the UE specific searchspace on NBIoT in NTN.

BRIEF SUMMARY

Methods and apparatuses for monitoring NPDCCH in NBIoT are disclosed.

In one embodiment, a method comprises receiving a first control signalscheduling a data transmission; and monitoring a second control signalfrom a start time slot to an end time slot, wherein the start time slotis a gap period behind the last time slot for receiving the firstcontrol signal, and the end time slot is a time period ahead of thefirst time slot for the data transmission.

In one embodiment, the gap period is configured by broadcast signal.Alternatively, the gap period is determined by at least one of UElocation information, and corresponding satellite orbit and ephemerisinformation.

In another embodiment, the method further comprises skipping monitoringthe second control signal during the gap period, wherein the first timeslot of the gap period is next to the last time slot for receiving thefirst control signal.

In some embodiment, the time period between the end time slot and thefirst time slot for the data transmission is two time slots.

In another embodiment, a remote unit comprises a receiver configured toreceive a first control signal scheduling a data transmission; and aprocessor configured to monitor a second control signal from a starttime slot to an end time slot, wherein the start time slot is a gapperiod behind the last time slot for receiving the first control signal,and the end time slot is a time period ahead of the first time slot forthe data transmission.

BRIEF DESCRIPTION OF THE DRAWINGS

A more particular description of the embodiments briefly described abovewill be rendered by reference to specific embodiments that areillustrated in the appended drawings. Understanding that these drawingsdepict only some embodiments, and are not therefore to be considered tobe limiting of scope, the embodiments will be described and explainedwith additional specificity and detail through the use of theaccompanying drawings, in which:

FIG. 1 illustrates a legacy NPDCCH search space;

FIG. 2 illustrates the legacy NPDCCH search space;

FIG. 3 illustrates an updated legacy NPDCCH search space;

FIG. 4 illustrates the monitoring of NPDCCH in the updated legacy NPDCCHsearch space;

FIG. 5 illustrates the monitoring of NPDCCH according to an embodiment;

FIG. 6 illustrates a situation in which the NPDCCH monitoring window ispositioned at the end of the gap period;

FIG. 7 illustrates a situation in which the NPDCCH monitoring window ispositioned in the beginning of the gap period;

FIG. 8 is a schematic flow chart diagram illustrating an embodiment of amethod; and

FIG. 9 is a schematic block diagram illustrating apparatuses accordingto one embodiment.

DETAILED DESCRIPTION

As will be appreciated by one skilled in the art that certain aspects ofthe embodiments may be embodied as a system, apparatus, method, orprogram product. Accordingly, embodiments may take the form of anentirely hardware embodiment, an entirely software embodiment (includingfirmware, resident software, micro-code, etc.) or an embodimentcombining software and hardware aspects that may generally all bereferred to herein as a “circuit”, “module” or “system”. Furthermore,embodiments may take the form of a program product embodied in one ormore computer readable storage devices storing machine-readable code,computer readable code, and/or program code, referred to hereafter as“code”. The storage devices may be tangible, non-transitory, and/ornon-transmission. The storage devices may not embody signals. In acertain embodiment, the storage devices only employ signals foraccessing code.

Certain functional units described in this specification may be labeledas “modules”, in order to more particularly emphasize their independentimplementation. For example, a module may be implemented as a hardwarecircuit comprising custom very-large-scale integration (VLSI) circuitsor gate arrays, off-the-shelf semiconductors such as logic chips,transistors, or other discrete components. A module may also beimplemented in programmable hardware devices such as field programmablegate arrays, programmable array logic, programmable logic devices or thelike.

Modules may also be implemented in code and/or software for execution byvarious types of processors. An identified module of code may, forinstance, include one or more physical or logical blocks of executablecode which may, for instance, be organized as an object, procedure, orfunction. Nevertheless, the executables of an identified module need notbe physically located together, but, may include disparate instructionsstored in different locations which, when joined logically together,include the module and achieve the stated purpose for the module.

Indeed, a module of code may contain a single instruction, or manyinstructions, and may even be distributed over several different codesegments, among different programs, to and across several memorydevices. Similarly, operational data may be identified and illustratedherein within modules and may be embodied in any suitable form andorganized within any suitable type of data structure. This operationaldata may be collected as a single data set, or may be distributed overdifferent locations including over different computer readable storagedevices. Where a module or portions of a module are implemented insoftware, the software portions are stored on one or more computerreadable storage devices.

Any combination of one or more computer readable medium may be utilized.The computer readable medium may be a computer readable storage medium.The computer readable storage medium may be a storage device storingcode. The storage device may be, for example, but need not necessarilybe, an electronic, magnetic, optical, electromagnetic, infrared,holographic, micromechanical, or semiconductor system, apparatus, ordevice, or any suitable combination of the foregoing.

A non-exhaustive list of more specific examples of the storage devicewould include the following: an electrical connection having one or morewires, a portable computer diskette, a hard disk, random access memory(RAM), read-only memory (ROM), erasable programmable read-only memory(EPROM or Flash Memory), portable compact disc read-only memory(CD-ROM), an optical storage device, a magnetic storage device, or anysuitable combination of the foregoing. In the context of this document,a computer-readable storage medium may be any tangible medium that cancontain or store a program for use by or in connection with aninstruction execution system, apparatus, or device.

Code for carrying out operations for embodiments may include any numberof lines and may be written in any combination of one or moreprogramming languages including an object-oriented programming languagesuch as Python, Ruby, Java, Smalltalk, C++, or the like, andconventional procedural programming languages, such as the “C”programming language, or the like, and/or machine languages such asassembly languages. The code may be executed entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the very last scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).

Reference throughout this specification to “one embodiment”, “anembodiment”, or similar language means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment. Thus, appearances of the phrases“in one embodiment”, “in an embodiment”, and similar language throughoutthis specification may, but do not necessarily, all refer to the sameembodiment, but mean “one or more but not all embodiments” unlessexpressly specified otherwise. The terms “including”, “comprising”,“having”, and variations thereof mean “including but are not limitedto”, unless otherwise expressly specified. An enumerated listing ofitems does not imply that any or all of the items are mutuallyexclusive, otherwise unless expressly specified. The terms “a”, “an”,and “the” also refer to “one or more” unless otherwise expresslyspecified.

Furthermore, described features, structures, or characteristics ofvarious embodiments may be combined in any suitable manner. In thefollowing description, numerous specific details are provided, such asexamples of programming, software modules, user selections, networktransactions, database queries, database structures, hardware modules,hardware circuits, hardware chips, etc., to provide a thoroughunderstanding of embodiments. One skilled in the relevant art willrecognize, however, that embodiments may be practiced without one ormore of the specific details, or with other methods, components,materials, and so forth. In other instances, well-known structures,materials, or operations are not shown or described in detail to avoidany obscuring of aspects of an embodiment.

Aspects of different embodiments are described below with reference toschematic flowchart diagrams and/or schematic block diagrams of methods,apparatuses, systems, and program products according to embodiments. Itwill be understood that each block of the schematic flowchart diagramsand/or schematic block diagrams, and combinations of blocks in theschematic flowchart diagrams and/or schematic block diagrams, can beimplemented by code. This code may be provided to a processor of ageneral purpose computer, special purpose computer, or otherprogrammable data processing apparatus to produce a machine, such thatthe instructions, which are executed via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions specified in the schematic flowchart diagramsand/or schematic block diagrams for the block or blocks.

The code may also be stored in a storage device that can direct acomputer, other programmable data processing apparatus, or otherdevices, to function in a particular manner, such that the instructionsstored in the storage device produce an article of manufacture includinginstructions which implement the function specified in the schematicflowchart diagrams and/or schematic block diagrams block or blocks.

The code may also be loaded onto a computer, other programmable dataprocessing apparatus, or other devices, to cause a series of operationalsteps to be performed on the computer, other programmable apparatus orother devices to produce a computer implemented process such that thecode executed on the computer or other programmable apparatus providesprocesses for implementing the functions specified in the flowchartand/or block diagram block or blocks.

The schematic flowchart diagrams and/or schematic block diagrams in theFigures illustrate the architecture, functionality, and operation ofpossible implementations of apparatuses, systems, methods and programproducts according to various embodiments. In this regard, each block inthe schematic flowchart diagrams and/or schematic block diagrams mayrepresent a module, segment, or portion of code, which includes one ormore executable instructions of the code for implementing the specifiedlogical function(s).

It should also be noted that in some alternative implementations, thefunctions noted in the block may occur out of the order noted in theFigures. For example, two blocks shown in succession may substantiallybe executed concurrently, or the blocks may sometimes be executed in thereverse order, depending upon the functionality involved. Other stepsand methods may be conceived that are equivalent in function, logic, oreffect to one or more blocks, or portions thereof, to the illustratedFigures.

Although various arrow types and line types may be employed in theflowchart and/or block diagrams, they are understood not to limit thescope of the corresponding embodiments. Indeed, some arrows or otherconnectors may be used to indicate only the logical flow of the depictedembodiment. For instance, an arrow may indicate a waiting or monitoringperiod of unspecified duration between enumerated steps of the depictedembodiment. It will also be noted that each block of the block diagramsand/or flowchart diagrams, and combinations of blocks in the blockdiagrams and/or flowchart diagrams, can be implemented by specialpurpose hardware-based systems that perform the specified functions oracts, or combinations of special purpose hardware and code.

The description of elements in each Figure may refer to elements ofproceeding figures. Like numbers refer to like elements in all figures,including alternate embodiments of like elements.

As described in the background part, unnecessary power consumption maybe present in monitoring the next DCI in the UE specific search space.FIG. 4 illustrates the monitoring of NPDCCH when the delay period isextended to k₀+K_(offset).

As shown in FIG. 4 , the UE, after receiving a first DCI N0 ending intime slot n (hereinafter, time slot is referred to as subframe), willstart the corresponding NPUSCH format 1 transmission starting fromsubframe n+k₀+K_(offset) (i.e. k=k₀+K_(offset)). In addition, the UEcontinues to monitor the NPDCCH from subframe n+1 to subframen+k₀+K_(offset)−3 for a next DCI N0 (a second DCI N0). The UE does notmonitor the NPDCCH at subframe n+k₀+K_(offset)−2 and subframen+k₀+K_(offset)−1 as these two frames are used for switching to theNPUSCH transmission. k₀ is determined by DCI N0. K_(offset) isconfigured by broadcast signal, e.g. in SIB or RRC signaling. K_(offset)may be alternatively determined by the UE when the UE has its positioninformation, and the earth orbit and ephemeris information. The earthorbit and ephemeris information indicates the position where thesatellite is.

Due to long RTD in NTN, the offset K_(offset) may be quite long.Therefore, it is power wasting to monitor the NPDCCH for the second DCIN0 during the entire period from subframe n+1 to subframen+k₀+K_(offset)−3.

FIG. 5 illustrates the monitoring of NPDCCH according to an embodimentof the present application.

As shown in FIG. 5 , the UE receives a first DCI N0 ending in subframen. Then, the UE skips NPDCCH monitoring from subframe n+1 to subframen+K_(offset). The UE monitors NPDCCH for a second DCI N0 from subframen+K_(offset)+1 to subframe n+K_(offset)+k₀−3. The UE is not required tomonitor NPDCCH for the last two subframes, i.e. subframen+K_(offset)+k₀−2 and subframe n+K_(offset)+k₀−1, used for switching tothe NPUSCH transmission. The UE starts NPUSCH format 1 transmissionindicated by the first DCI N0 from subframe n+K_(offset)+k₀.

It can be seen that, according to the present invention, if the NB-IoTUE detects NPDCCH with DCI Format N0 ending in subframe n, and if thecorresponding NPUSCH format 1 transmission starts from n+k (i.e.n+K_(offset)+k₀), the UE is not required to monitor an NPDCCH candidateduring a gap period, i.e. in subframes starting from subframe n+1 tosubframe n+K_(offset) nor during a time period (used for switching),i.e. from subframe n+K_(offset)+k₀−2 to subframe n+K_(offset)+k₀−1. Thefirst subframe of the gap period, i.e. subframe n+1, is just behind(i.e. next to) the last subframe for receiving DCI Format N0, i.e.subframe n.

From another point of view, if the NB-IoT UE detects NPDCCH with DCIFormat N0 ending in subframe n, and if the corresponding NPUSCH format 1transmission starts from subframe n+k (i.e. n+K_(offset)+k₀), the UEmonitors an NPDCCH candidate from a start subframe n+K_(offset)+1 to anend subframe n+K_(offset)+k₀−3.

The start subframe, i.e. subframe n+K_(offset)+1, is behind the lastsubframe for receiving DCI Format N0, i.e. subframe n, by the gap period(from subframe n+1 to subframe n+K_(offset)). In other words, the gapperiod (from subframe n+1 to subframe n+K_(offset)) is between the lastsubframe for receiving DCI Format N0, i.e. subframe n, and the startsubframe, i.e. subframe n+K_(offset)+1.

The end subframe, i.e. subframe n+K_(offset)+k₀−3, is two subframesahead of the first subframe for NPUSCH format 1 transmission (i.e.subframe n+K_(offset)+k₀). In other words, the two subframes used forswitching (subframe n+K_(offset)+k₀−2 and subframe n+K_(offset)+k₀−1)are between the end subframe (subframe n+K_(offset)+k₀−3) and the firstsubframe for NPUSCH format 1 transmission (subframe n+K_(offset)+k₀).

According to the present invention, for NBIoT in NTN with maximum HARQprocess number of 2, after reception a first DCI N0, UE will start tomonitor the NPDCCH for a second DCI N0 after the gap period, e.g., afterK_(offset) subframes.

The gap period may be configured by broadcast signal, e.g. by SIB orhigher layer. The gap period ranges from tens of milliseconds tohundreds of milliseconds. For example, if the eNB is on LEO, the gapperiod may be tens of milliseconds, while if the eNB is on GEO, the gapperiod may be hundreds of milliseconds. The gap period may bealternatively determined by the UE if the UE has its locationinformation, and the earth orbit and ephemeris information.

A NPDCCH search space is periodic. The length of the NPDCCH search space(i.e. NPDCCH period) may be indicated as T=G·R_(max), in which G isdetermined by higher layer, R_(max) is the maximum number of NPDCCHrepetition. The gap period may be represented in unit of NPDCCH period.For example, the gap period may be 10 NPDCCH periods (i.e.10T=10G·R_(max)).

A comparison between FIG. 4 and FIG. 5 can indicate that the UE does notmonitor NPDCCH for a next DCI N0 from subframe n+1 to subframen+K_(offset) according to the embodiment of the present invention (FIG.5 ) while the UE has to monitor NPDCCH from subframe n+1 to subframen+K_(offset) according to prior art shown in FIG. 4 . Therefore, powerconsumption for monitoring from subframe n+1 to subframe n+K_(offset)can be saved according to the embodiment of the present invention.

The NPDCCH monitoring window according to the present invention, i.e.from subframe n+K_(offset)+1 to subframe n+K_(offset)+k₀−3 as shown inFIG. 5 , is positioned at the end of the gap period between the lastsubframe for receiving DCI N0 and the corresponding NPUSCH transmission(in particular, 2 subframes (used for switching) ahead of the NPUSCHtransmission), rather than in the beginning or middle of the gap period.The position of the NPDCCH monitoring window is chosen in view offacilitating the scheduling, especially when the maximum HARQ processnumber is equal to 2.

FIG. 6 illustrates a situation in which the NPDCCH monitoring window ispositioned at the end of the gap period. FIG. 7 illustrates anothersituation in which the NPDCCH monitoring window is positioned in thebeginning of the gap period (e.g. following the DCI).

As shown in FIG. 6 , the second DCI is monitored at the end of the gapperiod between the first DCI and the corresponding first NPUSCH; thethird DCI is monitored at the end of the gap period between the secondDCI and the corresponding second NPUSCH. The scheduling is madesmoothly.

On the other hand, as shown in FIG. 7 , the scheduling will be blockedby the limited (two) HARQ process numbers.

As a whole, if the NB-IoT UE detects NPDCCH with DCI Format N0 ending insubframe n, and if the corresponding NPUSCH format 1 transmission startsfrom subframe n+k, the UE is not required to monitor an NPDCCH candidatein subframes starting from subframe n+1 to subframe n+K_(offset) andfrom subframe n+k−2 to subframe n+k−1 (assuming k=K_(offset)+k₀).

FIG. 8 is a schematic flow chart diagram illustrating an embodiment of amethod 800 according to the present application. In some embodiments,the method 800 is performed by an apparatus, such as a remote unit. Incertain embodiments, the method 800 may be performed by a processorexecuting program code, for example, a microcontroller, amicroprocessor, a CPU, a GPU, an auxiliary processing unit, a FPGA, orthe like.

The method 800 may include 810 receiving a first control signalscheduling a data transmission; and 820 monitoring a second controlsignal from a start time slot to an end time slot, wherein the starttime slot is a gap period behind the last time slot for receiving thefirst control signal, and the end time slot is a time period ahead ofthe first time slot for the data transmission.

FIG. 9 is a schematic block diagram illustrating apparatuses accordingto one embodiment.

Referring to FIG. 9 , the UE (i.e. the remote unit) includes aprocessor, a memory, and a transceiver. The processor implements afunction, a process, and/or a method which are proposed in FIG. 8 . TheeNB (i.e. base unit) includes a processor, a memory, and a transceiver.Layers of a radio interface protocol may be implemented by theprocessors. The memories are connected with the processors to storevarious pieces of information for driving the processors. Thetransceivers are connected with the processors to transmit and/orreceive a radio signal. Needless to say, the transceiver may beimplemented as a transmitter to transmit the radio signal and a receiverto receive the radio signal.

The memories may be positioned inside or outside the processors andconnected with the processors by various well-known means.

In the embodiments described above, the components and the features ofthe embodiments are combined in a predetermined form. Each component orfeature should be considered as an option unless otherwise expresslystated. Each component or feature may be implemented not to beassociated with other components or features. Further, the embodimentmay be configured by associating some components and/or features. Theorder of the operations described in the embodiments may be changed.Some components or features of any embodiment may be included in anotherembodiment or replaced with the component and the feature correspondingto another embodiment. It is apparent that the claims that are notexpressly cited in the claims are combined to form an embodiment or beincluded in a new claim.

The embodiments may be implemented by hardware, firmware, software, orcombinations thereof. In the case of implementation by hardware,according to hardware implementation, the exemplary embodiment describedherein may be implemented by using one or more application-specificintegrated circuits (ASICs), digital signal processors (DSPs), digitalsignal processing devices (DSPDs), programmable logic devices (PLDs),field programmable gate arrays (FPGAs), processors, controllers,micro-controllers, microprocessors, and the like.

Embodiments may be practiced in other specific forms. The describedembodiments are to be considered in all respects to be only illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

What is claimed is:
 1. A method comprising: receiving a first controlsignal scheduling a data transmission; and monitoring a second controlsignal from a start time slot to an end time slot, wherein the starttime slot is a gap period behind a last time slot for receiving thefirst control signal, and the end time slot is a time period ahead of afirst time slot for the data transmission.
 2. The method of claim 1,wherein, the gap period is configured by broadcast signal.
 3. The methodof claim 1, wherein the gap period is determined by at least one of userequipment (UE) location information, or corresponding satellite orbitand ephemeris information.
 4. The method of claim 1, further comprising:skipping monitoring the second control signal during the gap period,wherein a first time slot of the gap period is next to the last timeslot for receiving the first control signal.
 5. The method of claim 1,wherein a time period between the end time slot and the first time slotfor the data transmission is two time slots.
 6. A remote unit,comprising: a receiving circuitry; a transmitting circuitry; and aprocessor connected to the receiving circuitry and the transmittingcircuitry, the processor configured to cause the remote unit to: receivea first control signal scheduling a data transmission; and monitor asecond control signal from a start time slot to an end time slot,wherein the start time slot is a gap period behind a last time slot forreceiving the first control signal, and the end time slot is a timeperiod ahead of a first time slot for the data transmission.
 7. Theremote unit of claim 6, wherein, the gap period is configured bybroadcast signal.
 8. The remote unit of claim 6, wherein the gap periodis determined by at least one of user equipment (UE) locationinformation, or corresponding satellite orbit and ephemeris information.9. The remote unit of claim 6, wherein, the processor is furtherconfigured to cause the remote unit to skip monitoring the secondcontrol signal during the gap period, wherein a first time slot of thegap period is next to the last time slot for receiving the first controlsignal.
 10. The remote unit of claim 6, wherein a time period betweenthe end time slot and the first time slot for the data transmission istwo time slots.